INTRODUCTION. 
73 
row across the middle of the segments. The spi- 
nous caterpillars indigenous to Britain are but little 
remarkable when compared with many exotic spe- 
cies, but we have several which afford good examples 
of this description of defensive armour ; such, for 
instance, as the very common kinds that feed on the 
nettle. In these, and most other instances, the spines 
are sufficiently strong and sharp as readily to pierce 
the skin of the hand. They are very often beset with 
hairs, and frequently divide towards the top into se- 
veral small branches. Even when so numerous as 
entirely to cover the body, they are not placed pro- 
miscuously, but arranged, like the tubercles formerly 
mentioned, in a certain order. Each segment, with 
the frequent exception of that next the head, is arm- 
ed with a transverse series, varying in number from 
four to eight. The accompanying figure represents 
a magnified section of the caterpillar of Cynthi 
Cardui, exhibiting the number, mode of arrangement, 
and structure of the spines. (Plate II. fig. 5.) These 
appendages, in many foreign caterpillars, are said to 
sting like a nettle ; and there can be no doubt, that, 
in all cases, they are a powerful means of defence, 
not only against the smaller birds, * but even against 
more formidable enemies. 
• Few birds prey upon hairy caterpillars, although the 
Cuckoo which is extremely fond of the larva: of Arctia caja 
(called par excellence the hairy-worm) forms an exception 
to the rule. 
